1. Field of the Invention
The present invention relates to an apparatus for processing embroidery data used by an embroidery sewing machine to form an embroidery on a workpiece. More particularly, this invention is concerned with an apparatus for modifying stitch-position data representative of stitch positions, so as to enlarge selected local blocks of adjacent embroidery image patterns to be formed on the workpiece, so as to prevent undesirables gaps between mutually bounding blocks of the adjacent embroidery image patterns.
2. Discussion of the Related Art
In the field of industrial sewing machines, there is known an embroidery data generating apparatus using a microcomputer, which is capable of efficiently generating embroidery data for effecting an embroidering operation to form a desired embroidery on a desired workpiece such as a work fabric. For instance, such an embroidery data generating apparatus utilizes an image scanner and a mouse that are connected to a general-purpose personal computer, and is adapted to generate embroidery data on the basis of an original embroidery image.
The original embroidery image may consist of a single image pattern, or a combination of two or more image patterns which are positioned relative to each other as desired. An image pattern may be a character, for instance. In an example shown in FIG. 3, an embroidery image consists of a combination of three alphabetic letters "T", "E" and "L" which are arranged such that the adjacent characters are partially superimposed on each other.
To generate embroidery data for the original embroidery image of FIG. 3, the original image is read by an image scanner, and the outlines of the constituent image patterns in the form of the alphabetic letters "T", "E" and "L" are determined as indicated in FIG. 5. Then, the outline of each letter is divided into component blocks according to a suitably formulated blocking algorithm, as indicated in FIG. 6 by way of example only. The embroidery data include stitch-position data representative of stitch positions P1-P42, more precisely, the positions P1-P42 at which the needle of an embroidery sewing machine penetrates the workpiece to form stitches. The embroidery data including the thus generated stitch-position data are stored in a memory, and used by the sewing machine to effect an embroidery sewing operation wherein the needle and the workpiece (supported by a suitable work holder) are moved relative to each other, according to the stitch-position data, in a predetermined stitching direction. The stitching direction is determined for each block of each image pattern (alphabetic letter), as indicated by arrows in FIG. 6.
However, adjacent embroidery image patterns formed according to the conventionally generated stitch-position data suffer from the occurrence of gaps between mutually bounding blocks of the adjacent image patterns, which blocks are embroidered with stitches formed in the same direction. For example, block T3 of letter "T" and block E1 of letter "E" which are bounded by each other are embroidered in the same direction (horizontal direction as seen in FIG. 6). Consequently, the stitches formed in the block T3 cause a tension acting on the workpiece so as to pull the side P9-P10 of the block T3 away from the side P13-P15 of the block El. Similarly, the stitches formed in the block E1 cause a tension which pulls the side P13-P15 of the E1 away from the side P9-P10 of the block T3. As a result, an area of the workpiece along the adjacent sides P9-10 and P13-P15 of the blocks T3, E1 is exposed or is not covered by the stitches. Thus, the mutually bounding blocks which have been embroidered in the same direction tend to be more or less spaced apart from each other. Namely, gaps are created between the mutually bounding blocks.
The portions of the formed embroidery at which such gaps are created can be found by performing a test or trial embroidering operation on the workpiece. To avoid the occurrence of the gaps, the user or operator of the sewing machine should change or modify the originally generated stitch-position data representative of the outlines of the image patterns, so that the blocks that bound each other according to the original stitch-position data overlap each other by a suitable distance as measured from the original boundary. However, the procedure to change or modify the original stitch-position data is cumbersome and time-consuming, and may lead to an erroneous modification of the original stitch-position data.